PROJECT SUMMARY Our overarching goal is to increase enrollment, adherence and completion of cardiac and pulmonary rehabilitation (CR/PR) in a diverse population of low socioeconomic status; thus we will use a multi-pronged approach to increase referral, enrollment, adherence and completion. Our objectives are to 1) implement an EHR-based approach to increase referral to CR/PR, 2) evaluate the effect of choice of hospital or home-based rehabilitation on enrollment, adherence and completion and 3) evaluate the effect of nudge messaging on adherence and completion. This single site trial will be performed at Denver Health Medical Center, a large urban integrated safety net health system. We will provide all patients with the cellphone-based application, Movn, which will be used to deliver home-based rehabilitation and nudge messaging among patients randomized to those arms. In year 1 (R61 phase), we will 1) implement EHR-based interventions, 2) conduct a series of N of 1 trials to refine the nudge messages and tailor the interventions for diverse audiences, including Spanish-speaking patients, and 3) develop a one-page tool to present information, pros and cons of hospital and home-based rehabilitation for those randomized to choice. We will engage patients, providers, and health administrators to provide feedback on the messages and the information sheet, as well as engaging them in routine feedback during the study to help address potential barriers to implementation and help ensure sustainability. In the latter half of year 1, we will begin enrollment in the Phase II randomized trial. In years 2-5 (R33 phase), among patients eligible for CR or PR, we will conduct a patient level 2x2 randomized trial comparing: 1) hospital-based CR/PR and Movn alone; 2) hospital-based CR/PR and Movn with nudge messaging; 3) choice of hospital or home-based CR/PR and Movn alone; and 4) choice of hospital or home-based CR/PR and Movn with nudge messaging. The primary outcomes will be enrollment, adherence and completion of CR/PR. The study will also be evaluated using the RE-AIM framework.